Hawan karte time "Swaha" bolte hai uska kya meaning hota hai ?
"Swaha" of "Svaha" is basically a tribute to the devas (gods and goddess) requesting their blessings, empowerment etc (depending on exactly what one is doing) and is appropriate for anyone to use.
So for a general purpose when we just wish to chant a mantra to please god we use Namah - means I bow to you o lord.
When we do chanting for removing some disease or negativity or to get some thing from god then we use Swaha. With swaha mantra you have to sacrifice something.
so for example if we chant Shani mantra as Om Sri Shanaishwaraya Namaha , it will be for general purpose.